The present invention relates generally to the field of multi-port valves. More particularly, this invention relates to a multi-port valve for regulating, as a function of varying wind velocity and wind direction in an open-field control area, the distribution of a fluid in a fluid distribution system.
The chemical composition of the atmosphere has changed during the last century and will continue with exasperating speed to change in the future. A major cause of this change is the burning of fossil fuel which releases carbon dioxide (CO.sub.2) gas into the atmosphere. One affect of increasing levels or enrichment of CO.sub.2 in the atmosphere is an expected increase in plant photosynthetic rates and plant growth.
The United States Department of Energy and the United States Department of Agriculture are conducting cooperative research into investigating the effect of increasing CO.sub.2 enrichment on plants and ecosystems under a Free Air CO.sub.2 Enrichment (FACE) Program. Under the program, FACE systems have been set up to controllably release CO.sub.2 gas into open-field control areas. An objective of a FACE system is to maintain stable enrichment levels of CO.sub.2 over an open-field control area that is hundreds of square yards in size.
A FACE system generally consists of a circular array of 32 vertically extending vent pipes in which each vent pipe includes multiple gas emitter ports. Each vent pipe in the array vertically extends from and connects to a common toroidal distribution plenum that defines a generally circular open-field control area. A blower receives and mixes pure CO.sub.2 and ambient air prior to entry of the mixture into the plenum. The amount of CO.sub.2 mixed with ambient air entering the plenum is determined and controlled by a computer based on measurement of the wind velocity and CO.sub.2 concentration sampled at the center of the open-field control area. Emission of the CO.sub.2 enriched air from each vent pipe is individually controlled by the computer as a function of measurements, varying wind velocity and wind direction, taken in the open-field control area. Studies of enriched levels of CO.sub.2 in control areas containing various plants, such as cotton and pine trees, have been and continue to be conducted. In addition, pilot studies have been conducted using this same technology to enrich the atmosphere with ozone (O.sub.3) and sulfur dioxide (SO.sub.4).
There is a need for a multi-port valve that eliminates the need to individually control each vent pipe, to regulate, as a function of varying wind velocity and wind direction in an open-field control area, the distribution of a fluid in a fluid distribution system.